﻿using System;
using System.Collections.Generic;
using System.Text;

namespace Mozilla.UniversalCharacterDetection.Prober.StateMachine
{
    public class PkgInt
    {
        public static int INDEX_SHIFT_4BITS = 3;
        public static int INDEX_SHIFT_8BITS = 2;
        public static int INDEX_SHIFT_16BITS = 1;

        public static int SHIFT_MASK_4BITS = 7;
        public static int SHIFT_MASK_8BITS = 3;
        public static int SHIFT_MASK_16BITS = 1;

        public static int BIT_SHIFT_4BITS = 2;
        public static int BIT_SHIFT_8BITS = 3;
        public static int BIT_SHIFT_16BITS = 4;

        public static int UNIT_MASK_4BITS = 0x0000000F;
        public static int UNIT_MASK_8BITS = 0x000000FF;
        public static int UNIT_MASK_16BITS = 0x0000FFFF;

        private int indexShift;
        private int shiftMask;
        private int bitShift;
        private int unitMask;
        private int[] data;

        public PkgInt(int indexShift, int shiftMask, int bitShift, int unitMask, int[] data)
        {
            this.indexShift = indexShift;
            this.shiftMask = shiftMask;
            this.bitShift = bitShift;
            this.unitMask = unitMask;
            this.data = data;
        }

        public static int pack16bits(int a, int b)
        {
            return ((b << 16) | a);
        }

        public static int pack8bits(int a, int b, int c, int d)
        {
            return pack16bits((b << 8) | a, (d << 8) | c);
        }

        public static int pack4bits(int a, int b, int c, int d, int e, int f, int g, int h)
        {
            return pack8bits((b << 4) | a, (d << 4) | c, (f << 4) | e, (h << 4) | g);
        }

        public int unpack(int i)
        {
            return ((this.data[i >> this.indexShift] >> ((i & this.shiftMask) << this.bitShift)) & this.unitMask);
        }
    }
}
